A smart anti-corrosion coating based on triple functional fillers

The long-term anti-corrosion performance of ordinary coatings is unsatisfactory due to their poor barrier properties. Herein, we developed a strategy to construct a triple functional filler by first modifying basalt scales (Bt) with polydopamine (PDA) to introduce active sites, followed by in situ growth of molybdate-loaded layered double hydroxide (LM) on the surface of PDA-modified basalt. This novel strategy not only avoided stacking between LDHs, but also improved the interfacial compatibility between fillers and epoxy resin, which endowed the anti-corrosion system with intelligent self-healing function and barrier anti-corrosion characteristic. Tafel curves obtained in solution phase proved that compared with carbon steel immersed in pure 3.5 wt% NaCl solution, the introduction of Bt@PDA@LM causes the Icorr to decrease from 1.18 x 10(-5) A/cm(2) to 2.05 x 10(-6) A/cm(2) and the corrosion inhibition efficiency reaches 82.63%. Combined with the significant enhancement of the low-frequency impedance of the scratched Bt@PDA@LM/EP coating during immersion in 3.5 wt% NaCl solution, the effective corrosion inhibition of the designed filler was demonstrated. Moreover, the low-frequency impedance of the Bt@PDA@LM/EP coating is about 660 times higher than that of the pure epoxy (EP) coating after immersion in 3.5 wt% NaCl solution for 120 days and is still as high as 4.96 x 10(10) ohm.cm(2) after 200 days of immersion. The excellent corrosion resistance can be attributed to the synergistic effect of barrier property, chloride ion trapping effect and corrosion inhibition of the obtained filler. Thence, it is believed that this research will provide insights in developing new long-term anti-corrosion coatings and break the application limitations of polymer-based coatings to some extent.